The present invention relates generally to systems for controlling fluid flow, and in particular to medical infusion technology, although other embodiments are possible.
2. Description of Related Art
The precise and accurate regulation of fluid flow is required in many settings. Precision and accuracy are particularly vital in medical infusion rates. For example, in chemotherapy, too slow an infusion rate may prove inefficacious while too rapid a rate may prove toxic to the patient.
However, various elements inherent in medical infusion systems render problematic precise fluid delivery. One factor is the tubing that is used to deliver the fluid. Opening and closing of the line is typically accomplished by clamps, which can distort the walls of the tube leading to irregular flow rates. A second factor is that the patient receiving medication may move during infusion, producing varying fluid column heights, thereby affecting fluid flow. Third, the fact that fluid is delivered from a finite reservoir, such as an intravenous bag or bottle, that gradually empties, also affects the infusion rate.
Numerous approaches are known in the art to compensate for these factors. Certain prior art systems incorporate optical drop counting. Enhanced drop counting systems update drop count data with other measured quantities in order to compensate for varying drop size and splashing. Other approaches include bag weighing and pumping to regulate flow. However, systemic error is inevitable in most, if not all, of these arrangements.